Anti-jamming means for revolvers



April 6, 1965 H. N. HARRIS 5 3,176,422

ANTI-JAMMING MEANS FOR REVOLVERS Filed Fe'. 28, 1962 BY @u my ,4 Trae/VE V5.

3,176,422? Patented Apr. 6, 1965 tice 3,176,422 ANTI-JAIVIMING MEANS FOR REVULVERS Harlan N. Harris, Los Angeles, Calif.

(9981 Pali Ave., Tujunga, Calif.) Filed Feb. 2K8., 1962Ser, N r .176,288 1 Claim. (El. l2- 59) This invention relates tb firearms and, in particular, to

improvements in revolvers. l As increasing velocities are sought for revolver bullets, attempts are being made to increase the charge size over that which is attainable with the use `of acor'nmon straight case. One type of cartridge which has been suggested is the `sri-.called bottleneck cartridge wherein the case has a cylindrical portion of a first diameter and a reduced j neck holding the bullet. In this manner, a larger diameter cavity is provided for a charge, and the charge can therefore be made larger.

The bottleneck type of cartridge has not become popular principally because of its tendency to jam a revolver after being fired. It is an object of this invention to provide an improvement in the revolver which will enable a bottleneck cartridge or, vfor that matter, any other type of cartridge to be used more reliably and with less jamming.

This invention is carried outin a gun fof the class having a frame, a cylinder mounted in the frame, the cylinder having chambers for holding cartridges. A barrel is fixed in the frame and includes a bore which opens toward the cylinder, the cylinder `being rotatable on a shaft whereby different ones of the chambers can be brought into registration with the bore so that shellsmay be sequentially tired.

The frame includes a surface (some parts of which may bev on the end of a barrel threaded into the frame) which faces and is' spaced from an adjacent surface on the cylinder. These surfaces form an orifice fluidly interconnecting the bore of the barrel and the atmosphere.

A feature of this invention resides in a flow chamber in fluid communication with that end of the bore of the barrel adjacenttb the cylinder, which flow chamber opens onto said cylinder.` Some of the rgas that is generated by firing a cartridge, tl'ows into this now chamber, and exerts a pressure on ythe adjacent cylinder surface to push the cylinder away from the barrel when the gunV is fired. This eliminates the principal cause of a revolvers jamming, as wi11 lterbe shown. j j 1 According to aV preferred but optional feature of the invention, the now chamber is formed as a sink in the frame surface, the sink being y formed symmetrically around the b'ore of the barrel.

The above and otherfe'a'tures of this invention will be fully understood from the following detailed description and the accompanying drawings in which: v

FIG. l is a side elevation partly in cutaway crosssection showing the presently preferred' embodiment of the invention; j l p FIGS. 2-4 are fragmentary side views, partly in cutaway cross-section, showing alternate embodiments of the invention; and v n Y n FIG. 5 is across-section taken at line 5--5 of FIG. 1. FIG. l illustrates a revolver which includes a frame 11 hai/ing a slot 12 in which a rotatable cylinder 13 is mounted. The cylinder is mounted by means of a shaft 14 so that it is rotatable. There is a certain amount of axial end play in the shaft, the amount depending on tolerances permitted. In Vany practical gun, there will always be at least some possible axial movement of the cylinder.

Cylinder 13 includesV a plurality of chambers 15 for receiving cartridges 16; A conventional hammer-firing pin assembly 17 is provided for firing the shell.

A barrel 1S is threaded into an opening in the frame so as to become an integral part of the frame. The bore 19 of the barrel is aligned with a chamber position so it will receive bullets fired from the chamber. In FIG. l, the gun is shown just after being fired, with the bullet still in the bore.

A surface V2i) on the barrel, and a 'surface 21 on .the frame itself, both are adjacent to, spaced from, and face a cylinder surface 22. Because both surfaces 20 and 2.1 are rigidly interconnected members, they will be collectively referred to as a frame surface. An orince 23 is formed between the frame surface and the cylinder surface having a dimension of Width 24 measured parallel to axis 25 of the bore.

A flow chamber 26 is formed which is in iluid communication with the bore at the end' of the bore` which is adjacent to the cylinder. The llow chamber is in huid communication with the cylinder surface. It isdisposed between the bore and the orifice so that, when the bullet is fired and enters the bore of the barrel as illustrated 4in FIG. 1, some `of the gases behind the bullet Will flow into the flow chamber and out to atmosphere through the orifice. These gases, while in the flow chamber, exert va fluid pressure on cylinder surface 22, forcing it to the left in FIG. 1. l

Flow chamber 26 is preferably formed as a sink in one of the aforesaid surfaces, and symmetrically around the bore. In the preferred embodiment shown in FIG. l, a sink is formedin the frame surface and also in the cylinder surface. Sink 27 is formed 4in the frame surface (in this case entirely inthe material forming the barrel), and sink 2.8 isV formed in the cylinder surface. However, only one of these sinks need be provided. When the sinks are provided in the cylinder, they are preferably, but not necessarily, located symmetrically around the end of each of the ports adjacent to the barrel.

Flow chamber 216 provides `a region of greater flow area than the orifice with respect to huid now from the bore to the atmosphere past the frame and cylinder surfaces. The orifice thereby provides a flow restriction relative to the now chamber which tends to maintain fluid pressure therein at a higher value than if the orifice were not present.

In FIG. 2, there is shown a different type of sinkl which may be used. It also illustrates the fact that the sink need not be formed both frame and cylinder surfaces. In this embodiment, th'e sink is frusto-conical, and formed only in the frame surface on barrel 32.

FIG. 3 illustrates a frame 35l in which the end of the barrel 36 is recessed in the threaded hole 37 which receives the barrel to form ll'ow chamber 38. This ow chamber is a sink formed in the frame surface in the same sense as in the other embodiments. j

FIG. 4 illustrates the formation of a liow chamber i0 formed by a sink in the frame surface, in this case both t3 by recessing a portion of the material of the frame 41 itself, and also by either removing barrel material flush with the bottom of the sink, or by making the barrel initially of such length that it terminates in that position.

The operation of all embodiments will be understood from a consideration of FIG. l, and of what occurs in a conventional revolver when it is fired. When the charge is detonated, gases are produced which force the cartridge case to the left in FIG. 1, and expel the bullet to the right. As the bullet leaves the chamber, it exerts a frictional drag on the walls thereof and tends to carry the cylinder along with it to the right. This thereby axially shifts the relative positions of the cartridge case and the chamber. In a practical gun, there is always sufficient looseness of lit between the shaft and the frame as to permit of this axialshifting. The cartridge case is thereby shifted firmly against the left hand end of slot 12, and the cylinder is moved to the right.

Also, there is an expanding hoop effect of the cartridge case caused by the internal iiuid pressure. When a straight case is used, this expansion is limited by the wall of the chamber, so that the case does not change shape, even when the above-described shift occurs. Therefore, when the bullet has left the barrel, and the fluid forces have been reduced to atmospheric pressure, a cylindrical case will relax and be restored to its original configuration, and there will be no forces tending to keep the cylinder and the cartridge case in their axially shifted positions. When the cylinder is rotated, there is little, if any, binding between the shell and the frame.

However, when a bottleneck cartridge case is used and the shifting movement takes place in a conventional revolver, the case tends to expand at the tapered shoulder of the case, changing the shape of the shell while in the shifted position, to such an extent that even after the gas pressure is relieved by departure of the bullet from the bore, the case is held firmly against the frame, with the cylinder held at its forward-most location. This causes the gun to jam, because the cylinder cannot turn. In fact, it is often necessary to pry the cylinder toward the base shell with a tool in order to release the cylinder. This jamming occurs with sufficient frequency that bottleneck cartridges have become regarded as insufficiently reliable and therefore have not become popular.

This invention overcomes the tendency of the cylinder to shift to the right in FIG. 1 when the bullet departs, by forcing it to the left by pressure exerted in the flow chamber against the cylinder. Were the fiow chamber not to be provided and frame and cylinder surfaces were parallel and uniformly spaced apart, which is the conventional relationship in revolvers, it would be found that gas would simply escape through that orice without any substantial tendency to force the cylinder to the left. If, however, the gun is constructed in accordance with the invention, wherein a flow chamber of substantial volume exists in fiuid communication with the cylinder surface, then, instead of the gases merely jetting out through a uniform annular orifice without exerting much, if any,

yforce on the cylinder, pressure will build up in the substantial flow chamber shown, and be held there at least momentarily by the restricted orifice. Therefore, this arrangement results in a region of elevated pressure which can be made of the same order of magnitude as that taking place inside the case by appropriately adjusting the area of the flow chamber lin a plane normal to the bore axis. Furthermore, the area can be made greater than the cross-sectional area at the rear of the case, and preferably is so made, so that there is a net force to the left in FIG. 1. While the restraining force on the cylinder does not begin to occur until after the bullet has passed into the bore, still all reactions occur in extremely short periods of time, and are so nearly concurrent that changes in shape of the cartridge do not occur when the cylinder is all the way forward and the case all the way back.

fig, The following is a table of suggested dimensions for a cartridge revolver, caliber 25:

Diameter Area in in inches square inches Bore diameter of barrel .250 Groove diameter' of barrcL.. .257 ZV Diameter o lead or chamfer iu end of barrel 2 7 .OnoU Diameter of bullet 2oz -F Diameter of case body ..770 110.) Diameter oi flow chamber .500 .1964

Calculation .1964 sq. in. .0560 sq. in.

.1404 sq. inzarea of pressure acting on cylinder -.1105 sq. in.:area eros-section of case body .0299 sq in.:net area tending to hold cylinder in de- .sired position.

This invention, while it exists largely to make practical the use of bottleneck cartridge cases, is also applicable to straight cased cartridges and reduces the incidence of jamming.

Attention is called to a technique known to gun users by the term free boring, which constitutes a small chamfer at the end of the barrel opening adjacent to the cylinder which constitutes a guide surface for the bullet. It is conventional practice to form this gentle chamfer in the rified bore adjacent to the cylinder to allow for slight misalignment of the cylinder chambers relative to the barrel. The term sink or flow chamber is intended to encompass enlargements of the region of guns which generally face the cylinder surfaces outside the region where the bore customarily terminates.

This invention is not to be limited by the embodiment shown in the drawings and described in the description which are given by way of example and not of limitation, but only in accordance with the scope of the appended claim.

I claim:

In a gun having a frame, a cylinder mounted in the frame, said cylinder having chambers for holding cartridges to be fired, a barrel on the frame forming part of the frame and having a bore opening toward the cylinder, the cylinder being rotatable on a shaft whereby different ones of said chambers may be brought into registration with the bore, the frame including frame surfaces facing and spaced from an vadjacent cylinder surface on the cylinder by a first distance, thereby forming an orifice between the barrel and the atmosphere, the improvement comprising: a flow chamber in fluid communication with the end of the bore adjacent to the cylinder and opening onto said cylinder, said fiow chamber being formed by a sink in each of said surfaces, a sink being formed in the frame `surface around the bore, and a sink being formed in the cylinder surface around each chamber, the sink around the bore and each cylinder sink when aligned with the bore, being opposite from and facing each other, portions of each of said sinks then being spaced from portions of the opposite sink by a second distance which is larger than the first distance, said fiow chamber being peripherally surrounded by surfaces separated by the first distance, whereby some gases generated by firing a cartridge are discharged into the fiow chamber where they exert pressure on the said adjacent cylinder surface and thereafter flow through the orifice, the flow chamber thereby providing a region of elevated pressure which is exerted upon the cylinder to force the cylinder away from the barrel when the gun is fired.

References Cited in the file of this patent UNITED STATES PATENTS 756,182 Novak Mar. 29, 1904 970,248 v Lisle Sept. 13, 1910 1,499,163 Favini June 24, 1924 2,790,353 Bird Apr. 30, 1957 

